The Clinical Spectrum of Primary Cutaneous CD4+ Small/Medium-Sized Pleomorphic T-Cell Lymphoproliferative Disorder: An Updated Systematic Literature Review and Case Series.

BACKGROUND: Primary cutaneous CD4+ small/medium pleomorphic T-cell lymphoproliferative disorder (SMPLPD) is a provisional entity within the 2016 World Health Organization classification of primary cutaneous lymphomas. The condition is currently classified as a lymphoproliferative disorder to emphasize its benign course and discourage aggressive, systemic treatment modalities. OBJECTIVE: To provide a relevant synthesis for the dermatological practitioner on the prevalence, presentation, and treatment of SMPLPD. METHODS: We conducted an updated systematic literature review and a retrospective chart review of diagnosed cases of SMPLPD from 2 Canadian academic cutaneous lymphoma centers. RESULTS: A total of 23 studies with 136 cases were extracted from the systematic review and 24 patients from our retrospective chart review. SMPLPD proved relatively common accounting for 12.5% of all cutaneous T-cell lymphomas encountered in our cutaneous lymphoma clinics, second in frequency only to mycosis fungoides. The typical clinical presentation was that of an older individual (median age 59 years) with an asymptomatic solitary lesion on their upper extremity. The most common clinical differentials were cutaneous lymphoid hyperplasia, basal cell carcinoma, and lymphoma unspecified. T follicular helper markers were reliably detected. The main treatment modalities were surgical excision, local radiation therapy, and topical or intralesional steroids. Cure was achieved in the vast majority of cases. CONCLUSIONS: SMPLPD is an underdiagnosed T-cell lymphoma with an overtly benign clinical course. The condition has an excellent prognosis and responds well to skin-directed therapies. Practitioners should be aware of this condition to avoid aggressive systemic treatments.

The Neoantigen Landscape of Mycosis Fungoides.

Background: Mycosis fungoides (MF) is the most common cutaneous T-cell lymphoma, for which there is no cure. Immune checkpoint inhibitors have been tried in MF but the results have been inconsistent. To gain insight into the immunogenicity of MF we characterized the neoantigen landscape of this lymphoma, focusing on the known predictors of responses to immunotherapy: the quantity, HLA-binding strength and subclonality of neoantigens. Methods: Whole exome and whole transcriptome sequences were obtained from 24 MF samples (16 plaques, 8 tumors) from 13 patients. Bioinformatic pipelines (Mutect2, OptiType, MuPeXi) were used for mutation calling, HLA typing, and neoantigen prediction. PhyloWGS was used to subdivide malignant cells into stem and clades, to which neoantigens were matched to determine their clonality. Results: MF has a high mutational load (median 3,217 non synonymous mutations), resulting in a significant number of total neoantigens (median 1,309 per sample) and high-affinity neoantigens (median 328). In stage I disease most neoantigens were clonal but with stage progression, 75% of lesions had >50% subclonal antigens and 53% lesions had CSiN scores <1. There was very little overlap in neoantigens across patients or between different lesions on the same patient, indicating a high degree of heterogeneity. Conclusions: The neoantigen landscape of MF is characterized by high neoantigen load and significant subclonality which could indicate potential challenges for immunotherapy in patients with advanced-stage disease.

Phagosomal F-Actin Retention by Cryptococcus gattii Induces Dendritic Cell Immunoparalysis.

Cryptococcus gattii is a major cause of life-threatening mycosis in immunocompetent individuals and responsible for the ongoing epidemic outbreak of cryptococcosis in the Pacific Northwest of North America. This deadly fungus is known to evade important host immune responses, including dendritic cell (DC) maturation and concomitant T cell immunity, via immune evasion mechanisms that remain unclear. Here, we demonstrate that primary human DCs phagocytose C. gattii but the maturation of phagosomes to phagolysosomes was blocked as a result of sustained filamentous actin (F-actin) that entrapped and concealed the phagosomes from recognition. Superresolution structured illumination microscopy (SR-SIM) revealed that the persistent phagosomal F-actin formed a cage-like structure that sterically hindered and functionally blocked the fusion of lysosomes. Blocking lysosome fusion was sufficient to inhibit phagosomal acidification and subsequent intracellular fungal killing by DCs. Retention of phagosomal F-actin by C. gattii also caused DC immunoparalysis. Disrupting the retained F-actin cage with cytochalasin D not only restored DC phagosomal maturation but also promoted DC costimulatory maturation and robust T cell activation and proliferation. Collectively, these results reveal a unique mechanism of DC immune evasion that enhances intracellular fungal pathogenicity and may explain suppressed cell-mediated immunity.IMPORTANCECryptococcus yeast species typically display characteristics of opportunistic pathogens, with the exception of C. gattii, which can cause life-threatening respiratory and disseminated brain infections in otherwise healthy people. The pathogenesis of C. gattii is not well understood, but an important characteristic is that C. gattii is capable of evading host cell-mediated immune defenses initiated by DCs. Here, we report that when virulent C. gattii becomes ingested by a DC, the intracellular compartment containing the fungi is covered by a persistent protein cage structure consisting of F-actin. This F-actin cage acts as a barrier to prevent interaction with other intracellular compartments, and as a result, the DC fails to kill the fungi and activate important cell-mediated immune responses. We propose that this unique immune evasion mechanism permits C. gattii to remain unchallenged within host cells, leading to persistent infection.

Diagnostic challenge of aleukemic leukemia cutis preceding acute myelogenous leukemia: A case report.

Aleukemic leukemia cutis is a rare condition in which malignant white cells invade the skin before they appear in the peripheral blood or bone marrow. It is often associated with a poor prognosis. The condition presents a diagnostic challenge as its manifestations are quite variable terms of lesion type. It can manifest as papules, nodules, and/or plaques, and in rare cases erythematous macules, blisters, and ulcers. The most commonly affected areas of the body are the lower extremities, followed by the upper extremities, back, trunk, and face. Due to the non-specific presentation of the disease, skin biopsy and comprehensive immunohistochemical testing can be extremely helpful in the diagnostic work-up. We describe a case of leukemia cutis presenting prior to acute myelogenous leukemia that was initially misdiagnosed as hyper-IgG4 disease.

Beta3-Tubulin is Critical for Microtubule Dynamics, Cell Cycle Regulation, and Spontaneous Release of Microvesicles in Human Malignant Melanoma Cells (A375).

Microtubules (MTs), microfilaments, and intermediate filaments, the main constituents of the cytoskeleton, undergo continuous structural changes (metamorphosis), which are central to cellular growth, division, and release of microvesicles (MVs). Altered MTs dynamics, uncontrolled proliferation, and increased production of MVs are hallmarks of carcinogenesis. Class III beta-tubulin (ß3-tubulin), one of seven ß-tubulin isotypes, is a primary component of MT, which correlates with enhanced neoplastic cell survival, metastasis and resistance to chemotherapy. We studied the effects of ß3-tubulin gene silencing on MTs dynamics, cell cycle, and MVs release in human malignant melanoma cells (A375). The knockdown of ß3-tubulin induced G2/M cell cycle arrest, impaired MTs dynamics, and reduced spontaneous MVs release. Additional studies are therefore required to elucidate the pathophysiologic and therapeutic role of ß3-tubulin in melanoma.

Muffin Technique Micrographic Surgery for Non-melanoma Skin Cancer.

Background: Mohs micrographic surgery (MMS) is the gold standard treatment for high-risk facial non-melanoma skin cancer. However, patients' access to MMS is limited by cost. The muffin technique micrographic surgery (MTMS) is an alternative micrographic technique wherein the entire excised margin is evaluated post-operatively by a pathologist using paraffin-embedded material. Herein, we describe the implementation and the preliminary results of MTMS in an academic dermatology center. Objective: To describe the MTMS and outline its efficacy and safety in a real-world clinical academic setting. Methods: A retrospective chart review was conducted of all patients with basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) who underwent MTMS at the University of Alberta Dermatology Center from June 2016 until July 2019. Results: A total of 69 patients were included (64 BCCs and 5 SCCs). 68.1% of surgeries had clear margins following the first incision, 100% after second round re-excisions. There were no observed cases of tumor recurrence after a median 40 months of follow-up. There were no major adverse events or complications. Conclusions: MTMS is a superior alternative to simple excision of skin cancer by providing full margin control and residual tumor mapping.

Immunotherapy for Cutaneous T-Cell Lymphoma: Current Landscape and Future Developments.

Mycosis fungoides (MF) and Sézary syndrome (SS) are chronic, progressive primary cutaneous T-cell lymphomas (CTCLs) for which there are no curative treatments. Skin-directed therapies, such as phototherapy, radiation therapy, or topical nitrogen mustard, provide only short-term remissions. Numerous attempts with different chemotherapeutic regimes failed to achieve meaningful clinical responses. Immunotherapy seems to be a promising avenue to achieve long-term disease control in CTCL. There is compelling evidence indicating that MF and SS are immunogenic lymphomas, which can be recognized by the patient's immune system. However, CTCL uses different strategies to impair host's immunity, eg, via repolarizing the T-cell differentiation from type I to type II, recruiting immunosuppressive regulatory T-cells, and limiting the repertoire of lymphocytes in the circulation. Many currently used therapies, such as interferon-α, imiquimod, extracorporeal phototherapy, and allogeneic bone marrow transplant, seem to exert their therapeutic effect via activation of the antitumor cytotoxic response and reconstitution of the host's immune system. It is likely that novel immunotherapies such as immune checkpoint inhibitors, cancer vaccines, and chimeric antigen receptor-T cells will help to manage CTCL more efficiently. We also discuss how current genomic techniques, such as estimating the mutational load by whole genome sequencing and neoantigen calling, are likely to provide clinically useful information facilitating personalized immunotherapy of CTCL.

Skin cancer knowledge and photoprotective practices of organ transplant recipients.

BACKGROUND: Long-term use of immunosuppressive medications by organ transplant recipients (OTRs) leads to an increased risk of non-melanoma skin cancers (NMSCs). The objective of this study was to assess photoprotective knowledge and practices among OTRs and to identify predictors of poor sunscreen adherence and barriers to photoprotection. METHODS: A written survey was administered to 300 solid OTRs attending the Southern Alberta Transplant Program. Demographics, transplant and NMSC history, ultraviolet radiation (UVR) exposure, photoprotective knowledge and practices, and barriers to implementing photoprotection were collected. Relevant statistical analyses and univariate and multivariable regression models on sunscreen use were performed. RESULTS: One hundred and seventy-nine of the 300 respondents reported not using sunscreen most days despite 79.3% recalling have received photoprotection education. Of the surveyed OTRs, 45.7% reported no barriers to implementing photoprotective practices. On average, respondents scored 74.5% on a commonly used tool to assess photoprotective knowledge (SD 30.6%). In multivariable analyses, older age, male gender, and lack of post-secondary education were associated with lower rates of self-reported sunscreen use. The most commonly patient-reported barriers to photoprotection were "hassle/time consuming" (16.7%) and "sunscreen is uncomfortable or unpleasant" (10.0%). CONCLUSIONS: Despite OTRs self-reporting having received sufficient sun-protective knowledge and demonstrating reasonable recollection of photoprotective education on assessment, implementation of sun protection in the studied OTRs remains suboptimal.